1. Field of the Invention
The present invention relates to a lens barrel used in an imaging apparatus such as a digital still camera and a video camera, and more particularly to a lens barrel and an imaging apparatus including the lens barrel, wherein alignment for adjusting the relative positional relation between lenses provided in a barrel body can be performed easily and accurately with a simple structure.
2. Description of the Related Art
In general, a lens barrel included in an imaging apparatus such as a digital still camera and a video camera is provided with a lens aligning mechanism for adjusting the optical axes of lenses. Lens alignment by the lens aligning mechanism is classified into tilt alignment for tilting the optical axis of a taking lens and shift alignment for moving the taking lens in a direction perpendicular to the optical axis of the taking lens.
An existing shift alignment mechanism for a lens barrel is described in Japanese Patent Laid-open No. 2002-196206 (Patent Document 1), for example. The shift alignment mechanism described in Patent Document 1 is a mechanism for adjusting a deviation in the optical axes of lenses in a lens barrel. The lens barrel in Patent Document 1 includes a holding member for holding lenses, a storing member for storing the holding member, and a deviation adjusting mechanism for moving the holding member in a plane perpendicular to the optical axis to thereby adjust the position of the optical axis. The holding member is stored in the storing member in such a manner as to abut against a wall portion of the storing member from its image plane side, wherein the wall portion is formed inside the storing member so as to project toward the optical axis. The deviation adjusting mechanism has an operating portion mounted on the object side of the wall portion so as to be rotatably operated from the object side in performing the adjustment, wherein the operating portion has a pin eccentric from the axis of rotation of the operating portion. By the eccentric rotation of the pin, the holding member is moved in a plane perpendicular to the optical axis.
According to the lens barrel described in Patent Document 1, it is unnecessary to increase the diameter of the lens barrel in order to avoid the interference between the deviation adjusting mechanism and the other members stored in the storing member as in the case that the deviation adjusting mechanism is located on the image plane side of the wall portion of the storing member. As a result, the diameter of the lens barrel described in Patent Document 1 can be reduced.
Another existing shift alignment mechanism for a lens barrel is described in Japanese Patent Laid-open No. 2001-296463 (Patent Document 2), for example. A lens frame structure for holding a lens used in optical equipment such as a camera and a video camera is described in Patent Document 2. The lens frame structure described in Patent Document 2 includes a reference frame member, a lens member held by the reference frame member, and a supporting portion for supporting the lens member. The supporting portion supports the lens member in such a manner that the lens member is in contact with the reference frame member at two positions lying on a line perpendicular to the optical axis of the lens member and that the optical axis of the lens member can be tilted with respect to the reference axis of the reference frame member, i.e., tilt movement can be performed.
According to the lens frame structure described in Patent Document 2, the lens member is in contact with the reference frame member at two positions lying on a line perpendicular to the optical axis of the lens member, so that tilt movement, shift movement, and rotational movement can be independently performed, thereby allowing a minute operation. Accordingly, fine lens alignment can be performed.
However, the lens barrel described in Patent Document 1 has a problem such that the number of parts is large and the structure is complicated, causing an increase in overall size and an increase in cost.
On the other hand, in the lens frame structure described in Patent Document 2, a lens holding frame is fixed to a reference frame by an adhesive, and a fixed condition of the lens holding frame is maintained by only an adhesive force of the adhesive. That is, the existing lens frame structure does not include biasing means for holding the lens holding frame. Accordingly, an unwanted tilt occurs in the lens holding frame and the direction of placement of the lens barrel is limited in performing the lens alignment. Further, since the weights of the lens and the lens holding frame are supported by only the adhesive, there is a possibility that the lens may be misaligned due to an unexpected impactive force or the like.